Process for removing volatile solvents from polymerized substances



March 18, 1941. Q w, TYSON 2,235,127

PROCESS Foa REMovING kVoLA'lILPi soLvEN'rs FROM POLYMERIZED SUBSTANCES `liled Sept. 21, 1938 l BUTANE GAS OUTLET T035 REYVCLED GAUGE /oo roles* TfMP :from $221: /5

.Barn NE 70% .B u 7A ve GAS Alva Pal. YMEFE L lQufD I STEAMWJTLET l50 immediate volatilization of\ the solvent,y eithv Patented Mar. 18,l 19.4.1*-

UNITED STATES Paocnss Foit'aEMovmG voLA'rmn sor.- vEN'rs FnoM rommsmznn suns'raNcEs charles w. Tyson, summit, N.J assigner tu Standard Oil Development Company, a corporation of Delaware Animation september 21", 193s, serial No. 230,994'

-` 11 claims. `(cisco-94) This invention relates to processes for the manufacture and purification of polymerized iso-olensubstances, and relates particularly to methods for the puriiicatiom of high molecular weight polymers formed by the polymerization in solution of olen substances. y v

In the petroleum cracking industry, there are available valuablefwaste gases containing subm stantial percentages of ,unsaturated hydrocarbon compounds, and considerable proportions of the propylenes, butylenes and amylenes which are gaseous under ordinary conditions of temperature andpressure. and are readily separated from the higher molecular weight unsaturated compounds,

'.,andfrom hydrogen and ethylene.A These gaseous olens are readily polymerizable into high molecular weight polymer compounds bytheuse of such catalysts as'boron tri-nuoxjide, aluminum chloride and similar materials at low temperatures/ranging from -10,.C. down' to 100 C.

The polymerization may be continued to the formation of polymerized bodies having molecular weights ranging from 1,000 to 200,000. A particularly advantageous procedure is found in the polymerization of iso-butylene in the presence of solvent and refrigerant liquids.-v such as ethane, ethylene, propane, butane and the like, or ethyl chloride, or similar refrigerants and solvents. These solvent refrigeralnts may be utilized also for dissolving th "catalyst, to increase the'catalytic effect, for` the production of 4the desired polyirierized resins of` suitably high molecular weight. When, however, these'solvent and diluent substances are used, particularly 'if the higher boiling `solvents-such asV butane or ethyl chloride are used. diiculty is encountered inremoving the solvents'fron the polymer.' This removal is quite urgently necessary, since residual portions of the solvents, particularly .the .higher boiling solvents,

40 interfere with the desired solidity and other characteristics of the polymer substance.

The "present invention utilizes the steps of heating' the solution fgthe polymerized resin to" a substantially raised temperatureA (under pressure if desired) suiiicient to provide as sensible. heat-a substantial portion of the latent heat of,

vaporization ofthe solvent, and thereafter discharging the heated polymer solution into a containerat lower; or atmospheric pressure to cause f a with or without the presence of an atamary sur.

solvent.

' f Thus the invention consists of a system includnectedthe various supply pipelines for the isobutylene, the catalyst, the solvent-refrigerant `solvent from a polymer substance; to heat a polymer solution to a'temperature substantially above the boiling pointof the solvent and thereafter discharge it into a separatory chamber; and to dilute a polymer Vsolution with other gas preparatory to further heating and separation of the solvent by volatilization, t

' Other objectsV and structure details'of the invention, as Well as the process of the invention, will be apparent from the following description when read in connection with the accompanying drawing in which:

The single gure is diagrammatic representation of apparatus, including a reaction chamber.

a heater and a separatory chamber, for practicing the invention.

Referring to the figure, the reaction chamber I is supported in any convenient manner, and

connected by appropriate pipe leads to source of supply for the various reacting substances. Thus.

' the pipe line 2 is connected Ito a supply of liquid solvent-refrigerant; the pipe line 3 is connected to a' supply of iso-butylene; the pipe lis connected to a supply of the catalyst, which may b e boron trifluoride or may be aluminum chloride or other suitable catalyst, and the pipe line 5 is connected to a receiver for the volatilized diluentrefrigerant. v

'Ihe solution of polymer in the solvent-refrigerant is withdrawn from the reaction chamber I 'thronghla pipe line'S 'which 'is connected to a pump 'I which discharges the solution through a pipe!` to a receiver drum 9. This drum serves both as a warming means, and as a repressuring means, to provide sufdcient pressure to send the solution through the volatilizing coil. Connected to the drum 9 there is also a pipe line. II

. through which a supply of inert gas, preferably heated, is delivered for thev'repressuring. A bypass pipe line' I2 is connected between the pipe 8 and the outlet pipe I4 around the drum 9 to bypass the solutionl when the pump 'I provides sumcient pressure, andit is not desired to warm the solution in a first stage. These several pipe lines are controlled `by valves as shown. The pipe line I4 is connected to a steam jacketed heating coil I5 mounted within the steam Jacket I'B which issupplied with steam through the pipe line i'l, from which the condensate is drained by a pipe line I8. The heater :coil Il is connected to a sep- -aratory drum I9, and a throttle valve may be,

f provided therein if desired, although usually it is for discharge oi the volatilized solvent and vola-y tile polymer such as the dimer and trimer.

Pipe 22 leads to a separatory drum 23 in `which the solvent is cooled sumclently to condense any dimer and trimer which may be present in the solvent vapors. The dimer and trimer may be removed through a pipe line 215, and the volatllized solvent in the form of a gasis removed through a pipe 25. The pipe 2% leads to 26, and additional hot, inert gas may be supplied.

l carbon dioxide and alcohol in -a jacket arounda condensing equipment which may include a compressor, or may include a strongly cooled condenser coil; or the pipe line 25 may be connected with the pipe andthe gaseous solvent from both -may be condensed simultaneously into cold refrigerant-solvent for return through pipe 2 to the reaction chamber.

Auxiliary supplies of inert gas may be supplied to and mixed with the polymer solution, in the pipe It, the gas being delivered through the pipe to the drum I9 through the pipe 21 i'or stripping the last quantities of solvent from the polymer In practicing the process oi `this invention, the

iso-butylene is puriied by appropriate processes.

preparatory to the polymerlzingv-reaction. It is then passed to the reaction chamber I which desirably contains a solvent such as ethylene -or propane or butane and is provided with means'of refrigeration. The means'i'or refrigeration may y consist oi .a vcharge oi low boiling solvent, as above 50 described; orit may consist of an-'inert refrigerant liquid,vmixed with asuitable solvent, (that is, propane and ethyl chloride when aluminum chloride is used as catalyst) or it may ,consist oi' solid carbon dioxide with Aa suitable solvent with.`

in the reaction chamber, or it may consist of solid the reaction chamber. Alternatively, various other refrigerating systems are available, .such

as'A ammonia refrigeration through a jacket ,around the reaction chamber, or ethylene, propane, butane, etc., through a' carbon dioxide etc., as desired.

- The reaction chamberY I also contains a catalyst which may be gaseous, such as boron fluoride which dissolves in the solvent liquid in.- the reaction chamber along withthe purified oleiin `Agas; or the catalyst may be aluminum chloride dissolved in an appropriate solvent in the reaction vessel such las ethyl or methyl chloride. The polymerization reaction occurs` to yield the desired substance.

The polymerization is .desirably continued until the solvent in the reaction chamber I contains an amount o! polymer ranging from 20% to'30 When this concentration is reached,- -thef'slujacket, or liquid' tion of polymer may be inpart or preferably in whole withdrawn from the reaction chamber and lreplaced with fresh solvent for a continuation of clusion of inert gas under similar pressure from the pipe 26. The temperature oi the polymer solution is then brought up' to a point well above room temperature and to a point auch that the sensible heat of the solution aided bythe inert gas, and by the reduction of vapor pressure resulting from the'presence-of the inert gas is sum cient to provide for the latent heat of vaporization of the solvent. The heated solution is then discharged into the recciverdrum it.

The heatedcoil i5 may conveniently taHe the form of 1 inch internal diameter tubing, having a length of approximately feet. The steam jacket I5 may desirably contain steam at a pressure in the neighborhood of 50 to 100 pounds to the square inch. Th polymer solution may be received in the inlet end of the heater coll at a concentration of 20%v to 30% polymer, and at a temperature of -50 to -80 F. Under these circumstances the solution is very viscous, and this high viscosity is maintained during the passage of the solution through the heater coil. Because of this viscosity a pressure from 100 to'125 pounds to the square inch may be required from the pump l to -force the solution through the heater coil.A

The heated material is discharged from the outlet end of the heater coil i'at a. temperature 0i ,approximately v" C. The 'hot material is re- 'ceived in the separatory chamber I9 which is held at a pressure very slightly above atmospheric pressure.

It is preferable that the receiver 'i9 also be heated externally to maintain the temperature of the de-solvanized polymer at a point favorable to maximum plasticity or fluidity, both for the purpose of. aiding in the driving out oi.' the last traces of solvent and for facilitating the collection ofthe polymer in a 'softened or semi-fluid condition.

Under such conditions 'of temperature and pressure the solvent, whether in the presence of -inert gas, in addition to the polymer, or in the p resence of the polymer alone, is substantially completely vaporized as it leaves the end of the .heating coil' I5. The non-volatile polymer is carried along with the current pf volatilized solvent and is thrown on to the walls of the drum I9,

- or on to the Raushig rlngs\if such are used.

The volatilized solvent passes out irom the drum 1 I9 by way of the pipe 22, and the hot 4polymer collects in the bottom of the drum l from which it is removedthrough the pipe 2l.

The fluid polymer inits downward passage in the drum I9 comes in contact with the hot inert gas passed in through the pipe 21, andfis thereby emciently stripped of the last traces ,of volatile material.

It is found that in the operation of the process there are produced'not only the relatively 'high molecular weight non-volatile polymer which is the primary product, but there are also produced small amounts oi other polymers auch. as thedimer and trimler which are undesirable in the heavy polymer and are also volatile. These dimer and trimer polymers are also volatillzed and stripped from the heavy polymer' and are carried along with the volatile solvent into the recovery drum 23. The gases are cooled in the drumy 23 to approximately room temperature or a few degrees below, and the dimer and trimer are thereby condensed, separated from the gaseous solvent and withdrawn from the collector 23 through the pipe 24. These polymers are suitable for use as antiknock agents in gasoline type fuels. 4

'Ihe gaseous solvent leaves the collector 23 by way of the pipe 25, and because of the relatively high vapor pressure of the dimer and trimer polymers, appreciable quantities of the volatile solvent from the collector 23 may be` conveyed to the same compressor and compressed together since4 the eilluent gas from the reaction chamber I also contains perceptible quantities of dimer and trimer of isobutylene. Howeveryby the use of an inter-stage cooler between the successive stages of the compressor,

the cooling at the intermediate pressure is sufficient to condense substantially all oi' the dimer and trmer polymers which may be removed and the eilluent gas upon cooling after the second compressor. stage is substantially pure solvent.

which may be butane, ethylene, etc. free from dimer and trimer, according to the original solvent supplied to the reaction chamber I.

It will be observed that this process is particularly advantageous in connection with the manufacture of a polymer material having a moilecular weight within the range of 1,000 to 15,000, since While polymers within this range are veryviscous, they are suillciently fluid, especially at the elevated temperature within the drum I9, to ilovv therein and to ow out through the drain pipe 2I. The procedure is suitable for use with higher molecular weight polymers up to the point where the temperature required to produce a sufficient fluidity to remove the material from the drumI I9 is so high as to produce an undesired amount of depolymerization or cracking.

'I'he above embodiment describes broadly 'a process in which the separation of the solvent lfrom the polymer occurs at or above atmospheric pressure. In some instances it is desirable to conduct the operation at lower temperatures and pressures, and for this purpose the chamber I9 and the subsequent members of the system may be evacuated to 4pressures below atmospheric, thereby facilitating the separation of solvent from polymer and reducing the necessary temperatures.

Thus, the process of the invention provides a simple, convenient, method of removing the solvent from the heavy polymer, and for collecting the polymer, free from solvent'.

While there is above described but a single embodiment of the invention. it is possible to provide still other embodiments without departure from the inventive concept herein disclosed and it is therefore desired that only such limita.-`

tions be imposed upon the appended claims as are stated therein or required by the prior art.

'lghe invention claimed is:

l. In the preparation of a hydrocarbon polymer the steps oi.' polymerizing an oleiln in a solvent. heating the polymer solution to a temperature substantially above the boiling point .of the solvent, discharging the heated polymer solution into a receiver and separating the volatilized solvent from the non-volatile polymer.

2. Inthe preparation of a hydrocarbon polymer the steps ofV polymerizing an oleiln in a solvent. heating the polymer solution to a temperaturey substantially above the boiling point of the solvent at atmospheric pressure,. discharging the heated polymer solution into a receiver at atmospheric pressure and separating the volatilized solvent from the non-volatile polymer.

3. In the preparation of a hydrocarbon polymer the steps oi' polymerizing an oleiin in a solvent, heating the polymer solution under pressure toz a temperature substantially above the boiling' point of the solvent, discharging the heated poly mer solution into a receiver, separating the volatilized solvent from the non-volatile polymer, and

collecting the solvent free polymer in substantial masses. l

4. In the preparation pf a hydrocarbon polymer the steps of polymerizing an olen in a solvent, heating .the polymer solution toa temperature substantially above the boiling point ot the solvent at atmospheric pressure, discharging the heated polymensolution into atmospheric pressure and separating the volatilized solvent from the non-volatile polymer.

5. In the preparation of. a hydrocarbon polymer the steps of` polymerizingan oleiln in a solvent, heating the polymer solution under pressure to a temperature substantially above the boiling point of the solvent at atmospheric pressure,

discharging the heated polymer solutioninto atmospheric pressure, separating the volatilized. solvent from the non-volatile polymer', recovering the volatilized solvent by condensation, and collecting the, solvent free polymer in substantial masses.V

6'. The process of preparing a pure hydrocarbon polymer comprising in combination the steps of dissolving an oleiln and a Friedel-Crafts type catalyst in a solvent'at low temperature, to produce a polymer solution, forcing the polymer solution under high pressure through a heater coil, volatilinlng the heatedpolymer .solution at relatively llow pressure, and separating the vola.- tilized solvent from non-volatile polymer at an elevated temperature.

7. The process of preparing a pure hydrocarbon polymer comprising in combination the steps of dissolving isobutylene and a Friedel-Crafts type catalyst in a solvent vat low temperature, to produce a polymer solution, forcing the polymer solution-under high pressure through a heater coil, volatilizing' the heated polymer solution at 8. -The process of preparing apure hydrocarbon i polymer comprising in combination the steps oi dissolving isobutylene and a Friedel-Crafts type catalyst in a solvent at low temperature. to produce a polymer solution. forcing the. polymer solution with,heated inert gas under high preasure through a heater coil. volatilizing the heated polymer solution at relatively low pressure, and

separating the volatilized'solvent from non-vola.- tile polymer at an elevated temperature.

9. The process of preparing a pure polymer comprising in combination the steps of dissolving isobutylene and a, Friedel-Crafts type catalyst in a solvent at low temperature, to produce a polymer solution, forcing the polymer solution -under high pressurethrough a heater coil, volatilizing the heated polymer solution at relatively low pressure, separating the volatilized solvent from non-volatile polymer at elevated temperature, and cooling the volatilized solvent.

10. 'I'he process of preparing a.. pur polymer comprising in combination the steps of dissolving isobutylene and a Friedel-Crafts type catalyst in a solvent at low temperature, to produce a. polymer solution. forcing the polymer solution under high pressure through a heater coil, vola.-

tilizing the heated polymer solution at relatively low pressure, separating the volatilized solvent from non-volatile polymer at an. elevated temperature, cooling and condensing the volatilized solvent and returning it to the reaction chamber for reuse.

l1. In the preparation of a hydrocarbon polymer the steps of polymerizing an olen in a solvent, heating the polymer solution under pressure to -a temperature substantially abovelthe boiling point of the solvent at atmospheric pressure. discharging the heated polymer solution into atmospheric pressure, separating the'vola.- tilized solvent from the non-volatile polymer, collecting the solvent free polymer in substantial masses, and cooling -the voletiiized solvent and.' separating therefrom volatilizable polymer.

- CHARLES W. TYSON.

DlcLAsMER 2,235,127.-0harles W. T son, Summit, N. J. PROCESS Fon Rmavms VQLATILE SoLvENTs FROM oLYMEmzED SUBsTANcEs. Patent dated March 18l` 1941. Disclaimer led May 16, 1944, by the assignee, Jaecc, Incorporat Hereby disclaims claim 1 of said patent. [O c'al Gazette June 20, 1944.] 

